Having metabolic syndrome dramatically increases one’s risk of developing type 2 diabetes and cardiovascular disease. Metabolic syndrome is defined as a cluster of concurrent risk factors: central obesity, insulin resistance, glucose intolerance, hypertension and dyslipidemia (an imbalance of fats in the blood).
“Metabolic syndrome is a growing health problem in the United States impacting roughly one-third of our adult population,” says Dorothy Klimis-Zacas, a professor of clinical nutrition at the University of Maine and co-author of the two studies published in the Journal of Nutritional Biochemistry and British Journal of Nutrition. “We are pleased to report our research indicates that wild blueberry consumption can have significant and positive health impacts on several components of this serious health condition.”
Kitty Broihier, a nutrition advisor to the Wild Blueberry Association of North America, concurs, stating, “Studies like these help make the case that including wild blueberries in your daily diet may have a positive impact on some of the risk factors involved in metabolic syndrome.”
The two studies were conducted on obese Zucker rats, which are a commonly used experimental model for studying metabolic syndrome in humans due to similarities in characteristics and disease progression. For both eight-week studies, the rats received a diet enriched with wild blueberries in an amount equivalent to two cups of berries per day for humans. The first study focused on examining markers of inflammatory status and their gene expression. Chronic inflammation is thought to be an underlying factor linking all the abnormalities of metabolic syndrome.
“Diet is one of the most manageable ways to impact inflammatory status, and our study documented for the first time that supplementing your diet with wild blueberries for eight weeks resulted in an overall reduction of the inflammatory status in the animals,” explains Klimis-Zacas. According to the researcher, this was achieved by reducing the circulating levels of two pro-inflammatory status markers and increasing the levels of anti-inflammatory markers, which resulted in positively impacting the gene expression of these markers as well.
The second study examined a wild blueberry-enriched diet’s impact on lipid metabolism and cholesterol levels. After eight weeks, there was a markedly beneficial impact on the obese Zucker rats’ lipid profiles: total blood cholesterol and triglyceride levels decreased, while beneficial HDL levels were maintained. The dietary treatment also favorably affected the expression of key enzymes involved in lipid and cholesterol metabolism.
“Wild blueberries appear to function by decreasing fat synthesis, increasing fat oxidation and aiding in reverse cholesterol transport, thus normalizing the abnormal lipid profile associated with metabolic syndrome,” summarized Klimis-Zacas.
Although these studies focused on the effects of whole-berry consumption, and not on the specific contributions of the bioactive components of wild blueberries, it is important to note, said Klimis-Zacas, that several previous studies suggest that the anthocyanin content of wild blueberries may be responsible for modifying risk factors for metabolic syndrome.
For more information about the studies go to: Journal of Nutritional Biochemistry (2013) 24:1508-12 – S. Vendrame, A. Daugherty, A.S. Kristo, P. Riso. D. Klimis-Zacas. Wild blueberry (Vaccinium angustifolium) consumption improves inflammatory status in the obese Zucker rat model of the metabolic syndrome. http://www.jnutbio.com/article/S0955-2863(12)00308-7/abstract
British Journal of Nutrition (2014) 111:194-200 S. Vendrame, A. Daugherty, A.S. Kristo, D. Klimis-Zacas. Wild blueberry-enriched diet (Vacciniumangustifolium) improves dyslipidemia and modulates the expression of genes related to lipid metabolism in obese Zucker rats.03/31/2015 The Ellsmorth American